1. Field of the Invention
The present invention relates to heat exchanger assemblies arranged in a specific configuration. More particularly, the present invention concerns apparatus and a method for assembling a heat exchanger in an inverted V-shaped configuration.
2. Prior Art
Air conditioning units as are typically used for conditioning a residence include split system components. In a split system, an outdoor condensing unit is typically mounted exterior of the residence in communication with outdoor ambient air and includes the heat exchanger serving as a condenser and the compressor. An indoor heat exchanger is mounted within the residence in the air flow stream of the air being circulated within the enclosure. This indoor heat exchanger is typically the evaporator of the air conditioning system.
It has been found advantageous to angle the heat exchanger serving as an evaporator to the air flow stream such that the desired amount of face area of the evaporator is presented to the air being circulated thereover. A single coil core may be angled across the entire air flow stream. Typically, a fan is additionally provided for circulating air from the enclosure through the indoor heat exchanger and back to the enclosure.
One of the specific configurations found highly acceptable for use as an indoor heat exchanger is an inverted V-shaped coil arrangement otherwise known as an A coil. In the inverted V-shape, two coil cores are positioned to be inclined to the air flow stream and to meet at the center of the air flow stream and extend downwardly and outwardly therefrom. Air may then flow upwardly through the coil cores and outwardly such that the air flows through the two coil cores in the inverted V-shaped arrangement. This arrangement is particularly advantageous because the face area of the two coil cores is larger than the cross-sectional area of the air flow stream. Additionally, by providing shorter angled coil cores, the air pressure drop of the air being circulated therethrough is decreased. Finally, by providing shorter inclined coil cores, the potential for condensate collecting on the heat exchange surface and dripping from the heat exchange surface downwardly into a fan or into a furnace is reduced since the water flow path along the heat exchange surface to the condensate collection area is reduced in length in an inverted V-shaped configuration.
One of the methods of assembling an indoor heat exchanger includes mounting a plurality of parallel plate fins, each defining openings, to form a fin bundle. Tube sheets are then placed at each end of the fin bundle and hairpin tubes are inserted through the openings of the tube sheets and the fin bundle to form a portion of a refrigerant flow path therethrough. The open end of the hairpin tube extending beyond the tube sheet is belled outwardly and return bends, U-shaped connecting pieces, are joined to the belled ends of the hairpin tubes to form appropriate connections to define a refrigerant flow path through the heat exchanger. The return bends are typically soldered to the hairpin tubes to complete the circuit. Special soldering processes are required if the heat exchanger materials are all aluminum.
One of the special processes utilized is to immerse the return bends and bell ends to be soldered into a molten solder bath and to apply ultrasonic energy whereby the return bend is bonded to the hairpin tube via this ultrasonic soldering process. Each of the two coil cores making up the inverted V-shaped assembly must be immersed in the solder bath and soldered. Since it is awkward and requires solder pots larger than presently available to solder the two coil cores in the inverted V-shaped configuration, heretofore the coil cores have been soldered separately and then assembled to form the desired heat exchanger.
The present invention concerns providing a single tube sheet having separate areas of spaced openings to receive the hairpin tubes cooperating with the fin bundles to define two separate coil cores. Each tube sheet defines a bending slot which extends across the face of the tube sheet but not across a coacting flange such that the remaining flange connecting portions serve as both a pivot point for allowing bending to change the configuration of the two coil cores relative to each other but also serve to maintain the two heat exchangers in the appropriate configuration. To effect soldering, the two coil cores are placed into a parallel side by side relationship such that the connecting portions are bent to form a 180.degree. angle. The two coil cores are then soldered simultaneously by immersing both of them in the solder pot while they are maintained in a parallel side by side relationship. Thereafter, the two coil cores are removed from the solder pot and displaced relative to each other to partially unbend the flange connecting portions to form the desired inverted V-shaped configuration.